The crude oil emulsions are water dispersions of water droplets in crude oil, which cannot be grouped, due to the presence of surfactant molecules naturally present in petroleum. These emulsions are frequently encountered during petroleum production and in the reservoir or during refining, transport and storage.
These emulsions are undesirable not only because they cause serious problems in the refining of oil, but also significantly increase operating costs, producing difficulties in transportation and damage the equipment due to corrosion and fouling problems.
The demulsifiers most used today in the oil industry are: compounds of the alkylphenol-formaldehyde type, ethylene and propylene oxide copolymers, alkoxylated amines, alkoxylated epoxy resin, dissolved in one or more solvents such as xylenes, toluene, naphtha and short chain alcohols. The mechanism of action promotes coalescence of water droplets into larger droplets, which then flocculate thus achieving the separation of two phases. It has also been established that the function of a good demulsifier is to alter the rheological properties of the interfacial layer and destabilize the oil endogenous emulsifier layer. Usually, commercial demulsifiers are a mixture of several components with different polymer structures and a broad molecular weight distribution (Al-Sabagh A M et al 2002).
For example, U.S. Patent Publication No. 2009/0306232 discloses the use of formulations prepared from various aliphatic and aromatic anhydrides, especially acetic and propionic, and applied together with other demulsifiers as alkylphenol resins, alkoxylated amines, glycolic esterified resins, and derivatives thereof. The proportion of acetic anhydride can vary from 0.5% up to 99% by weight, without indicating the kind of oil treated, which indicates that only contains 15% water by volume. The formulations were prepared in aromatic solvents or alcohols (Williams D E, 2009)
U.S. Patent Publication No. 2009/0259004, discloses the use of formulations dissolved in aliphatic and/or aromatic alcohols, water, fatty acid esters, ethers and combinations thereof, consisting of polyethers, polyesters or polyurethanes polyesters, which are synthesized from a polytetramethylene glycol and alkylene glycol or an alkoxylated amine, joined by a carboxylic diacid or a diisocyanate, said combination was applied without specifying which oil. The above formulations are prepared by tetramethylene from 5% to 90% by alkyleneglycol from 1% to 50% and difunctional coupling agent from 5% to 90%. Another main feature is that these kinds of demulsifiers are biodegradable (Newman S P et al, 2009).
U.S. Patent Publication No. 2008/0207780 discloses a class of demulsifiers synthesized from polyacids and multiepoxides among others. The formulations that were found to be biodegradable were applied on ultra-light and heavy crudes (Wang W, 2008).
U.S. Patent Publication No. 2006/0036057 describes the use of formulations as demulsifiers in crude oil, bitumen, distillates and mixtures thereof; demulsifiers formulations are prepared by the reaction of one or more alkylphenol-formaldehyde resins and by one or more polyalkylene glycols, individually or mixture thereof with phosphorus compounds of phosphorus oxychloride, phosphorus pentoxide and phosphoric acid type. These formulations can be applied individually or in combination with other compounds known and applied in crudes with API gravity=15 (Lang F T, 2006).
U.S. Pat. No. 5,401,439 apply formulations of alkoxylates based on alkylphenol-formaldehyde resins, polyalkylenepolyamine and bisphenols, all of them propoxylated and ethoxylated, whose main characteristic is that their polydispersity has a minimum value of 1.7. The addition was performed in the concentration range of 1 ppm to 1000 ppm in crude oils of German origin without indicating its API gravity (Elfers G, et al 1995).
WO 02/072737 (Varadaraj R and Brons C H) (2002) discloses the application of formulations demulsifiers in crude oils with API gravities between 5 and 30, prepared from 10 and up to 80% by weight of aromatic compounds that have at least 2 aromatic rings, alkylated with linear and/or branching chains of at least 16 carbon atoms and an ether of dipropylene monobutyl type or diethylene glycol monobutyl in proportions ranging from 90% to 20%. The addition was performed at concentrations from 5 to 10000 ppm preferred range being from 20 to 40 ppm.
By the above and by economic and operational reasons it is important to remove water, as well as minimizing the water content also decreases the amount of salts and corrosion risks while optimizing the transport of oil through the ducts.
For years, in the Molecular Engineering Program, we have addressed the problem of dehydration and desalting of crude oil from different points of view and so far there have been three patent applications, two of them describe the use of formulations of triblock copolymers of polyethylene oxide-polypropylene oxide-polyethylene oxide type with molecular weights in the range from 1000 to 4000 Daltons and are bifunctionalized with amines, for demulsifier and dehydrate heavy oil, which water concentration content ranges from 5 to 50% by weight, preferably 5 to 40% by weight; and they succeeded water removal in the order of 30 to 80% and salts removal in the range of 30 to 65% of heavy oil. (Cendejas G, et al 2008, Cendejas G, et al 2009).
